Structural birth defects are the leading cause of infant mortality in the US and have an enormous physical and emotional public heath impact. Understanding their etiology requires thorough knowledge of the basic underlying mechanisms associated with the development of organ systems, including the central nervous system. Basic research using animal models is uncovering the factors that trigger and control developmental processes. Neural tube defects (NTDs), which include spina bifida and anencephaly, are one of the most frequent and severe developmental anomalies of the central nervous system. This contract supports mouse models of neural tube defects. It was originally issued in 1989 to establish a centralized, national resource. By supporting this resource, scientists interested in studying this important abnormality have ready access to these unique research animals. Currently, the primary objectives of this contract are to 1) maintain mouse strains with neural tube defects, 2) distribute breeding pairs of mice from these strains on request to investigators in the scientific community and 3) develop and evaluate potential new mouse models.